1. Field of the Invention
The present invention relates to an apparatus and method for measurement of temperature using oscillators, and more particularly, to an apparatus and method for measurement of temperature using a frequency difference between a signal generated by an oscillator having high sensitivity to temperature and a signal generated by an oscillator having low sensitivity to temperature.
2. Description of the Related Art
A configuration of a temperature sensor manufactured using a conventional CMOS (Complementary Metal Oxide Semiconductor) process is as shown in FIG. 1. Referring to FIG. 1, a conventional CMOS temperature sensor includes a temperature detector 101 for detecting temperature, a reference unit 103 for providing a reference independent of temperature change, and an analog-to-digital converter (ADC) 105 for converting an analog signal received from the temperature detector 101 and the reference unit 103 into a digital signal. The temperature detector 101 employs a circuit to produce an output voltage in proportion to temperature using a portion of a band gap reference circuit or make the amount of a delay, which is produced by a delay line such as an inverter, proportional to temperature, or is designed to generate a signal in proportion to temperature using a special device. The reference unit 103 is mostly implemented using a band gap reference circuit or a delay line less sensitive to temperature. The analog-to-digital converter 105 is mostly an ADC of a sigma-delta type, a successive-approximation register type or a double integration type or alternatively may be implemented using a comparator or a time-to-digital converter.
However, the temperature sensors manufactured using the above mentioned conventional circuit techniques have problems of high sensitivity to temperature and high power consumption due to their analog characteristics. Moreover, these temperature sensors have problems of big circuit size due to complicated implementation and difficulty in incorporating with other electronic circuits, such as a DRAM (Dynamic RAM) or a microprocessor, into a SoC (System on a Chip).